A system for determining the state-of-health of batteries has an adaptive component. The system tests a battery by measuring a number of electrochemical parameters and using fuzzy logic to compute a state-of-health for the battery. The fuzzy logic computations are based upon membership functions which are preferably triangular. The membership functions may be stored in a matrix. The adaptive component adapts the system for use with new models of battery by obtaining a reliable measurement of SoH for a number of calibration batteries. Electrochemical parameters of the calibration batteries are measured. The adaptive component modifies a prototype matrix selected to match the chemistry type of the calibration batteries by scaling, translating and flexing its membership functions to achieve a matrix which specifies membership functions suitable for assessing state-of-health of the new model of battery.